We investigated the effects of radio frequency electromagnetic fields (RF
EMF) similar to those emitted by mobile phones on waking regional cerebral
blood flow (rCBF) in 12 healthy young men.

Two types of RF EMF exposure were
applied: a 'base-station-like' and a 'handset-like' signal. Positron
emission tomography scans were taken after 30 min unilateral head exposure
to pulse-modulated 900 MHz RF EMF (10 g tissue-averaged spatial
peak-specific absorption rate of 1 W/kg for both conditions) and sham
control.

We observed an increase in relative rCBF in the dorsolateral
prefrontal cortex on the side of exposure. The effect depended on the
spectral power in the amplitude modulation of the RF carrier such that only
'handset-like' RF EMF exposure with its stronger low-frequency components
but not the 'base-station-like' RF EMF exposure affected rCBF.

This finding
supports our previous observation that pulse modulation of RF EMF is
necessary to induce changes in the waking and sleep EEG, and substantiates
the notion that pulse modulation is crucial for RF EMF-induced alterations
in brain physiology.